7
Diagnostics and Troubleshooting
Troubleshooting
134
TSQ Quantum XLS and TSQ Quantum GC User Guide
Thermo Scientific
Some chemical noise does occur, such as septum bleed after a series of injections, vial sample
bleed (which occurs if more than one injection is made from a sample vial), and siloxane peaks
that appear in the chromatogram at regular intervals from focusing at the head of the column
or in the injector.
Other possible contamination sources include hydrocarbon contamination of the carrier gas,
pump oil, or instrument cleaning solvents.
Always wear clean, lint- and powder- free gloves when handling ion source and mass analyzer
components, and ensure that the carrier gas filter, carrier gas lines, and gas regulators are free
of contamination and leaks.
Issue:
Excessive
chemical background
due to a column bleed
(
m/z
429, 355, 281).
Possible causes/solutions
• The capillary column has not been properly conditioned. Condition the capillary
column.
• The capillary column is damaged as a result of exposure to oxygen. Find the source of the
oxygen in the carrier gas or air leak. Recondition or replace the capillary column.
Issue:
Excessive
injection port septum
bleed (Typical
m/z
207,
429, 355, 281).
Possible causes/solutions
• The septum is worn out or damaged. Replace the septum.
• Small pieces of septum are in the injection port liner. Replace the injection port liner;
condition the capillary column.
Issue:
Phthalate
background (
m/z
149,
167, 279).
Possible causes/solutions
• Phthalate contamination has occurred due to sample handling or solvent contamination.
• Packaging materials could be the source of phthalates.
• Isolate source of phthalates such as vial lids or plastic solvent containers and remedy.
Issue:
Excessive
hydrocarbon
contamination (Typical
ions are
m/z
43, 57, 71,
85, 99).
Possible causes/solutions
• Carrier gas tubing is contaminated.
• Isolate source of hydrocarbon contamination and remedy.
• Replace carrier gas tubing.
• Change carrier gas filters.